Thermoelectric safety device



Oct. 7, 1941. s. wUNscH EI'AL THERMOELECTRIQ SAFETY DEVICE OriginalFiled Aug. 3, 1934 INVENTORS 6' M210 M502 J JOJefJc/iappaz! 1mm JIM/1MATTORNEYS Patented Oct. 7, 1941 THEBMOELECTRIC sm'rr nsvrcs GuidoWilnsch. Berlin-Stealth, a Josef Schnppertbesaan,

Germany,amignors. meme assignments. to Junkers 6 0. m. b. 8., Dessau,Germany, a company ofGermany application August a, 1934. w No. 738,870.Divided and this application November 9, 1939, Serial No. 303,586.

Germany September 28, 1933 'IClaims.

This invention relates to an improvement in thermo-electric safetydevices and the like.

The present application is a division of our copending application.Serial No. 738,370, flied August 3, 1934.

While the particular device which we shall describe in connection withthe drawing is a thermoelectric safety valve, it is to be understoodthat the invention is not limited to use with this particular type ofdevice but may be employed in connection with thermoelectric safetyswitches and all similar devices as suitable and desired.

Thermoelectric safety devices which have a valve or other controllingmember. an electromagnet, and an armature which, when attracted, holdsthe controlling member in operative position and when retracted releasesthe controlling member for movement to safety position, require resetmeans for resetting the same.

These reset devices which move the armature to attracted position andthe controlling member to operative position have had the objection ofrequiring the operator to hold the armature in attracted position andthe valve, switch or other controlling member in operative positionuntil the pilot or other burner, to the heat of which the thermocouplewhich is connected in circuit with the electromagnet is subjected, islighted and, by the heat thereof on the thermocouple, has generatedsuflicient thermoelectric current to hold the armature in attractedposition and the valve or other controlling member in operativeposition.

According to our invention we provide means which, upon completion ofthe resetting of the armature to attracted position and the valve hrother controlling member to operative position, is operative to retardor delay movement of the armature to retracted position and movement ofthe valve or other controlling member to closed or safety position for asufficient length of time to permit the pilot or other burner to belighted and the heat of the fiame'thereof on the thermocouple togenerate suiiicient thermoelectric current to hold the armature inattracted position and the valve or other controlling member in open oroperative position.

The chief advantage of our invention is in the ability to reset thethermoelectric safety device by merely actuating the reset means andwithout requiring the operator to hold the armature in attractedposition and the controlling member in operative position for a periodof time in the resetting operation.

Another advantage of our invention is in the form of the retarding ormovement delaying means. and its disposition and correhtion with respectto the reset means and with respect to the electromagnet, armature andvalve or controlling member.

Other advantages and adaptations of the invention will be apparent fromthe following detailed description, taken in connection with theaccompanying drawing, in which the single figure is a diagrammatic view,partly in section, of one illustrative embodiment of the invention.

In the following descrmtion the invention will be described in itsapplication to heating apparatus, but it will be apparent to thoseskilled in the art that the broader aspects of the invention areapplicable to other apparatus in which the use of a safety device of thecharacter herein set forth is desired.

Referring to the drawing, the thermoelectric safety device is shown inits application to heating apparatus using gas as a heat generant. It isto be understood that any other fuel may be employed and that theheating apparatus may be of any suitable or preferred form, dependingupon the requirements thereof.

The gas may be supplied from any suitable conventional source of supply(not shown) to a bumer or burners 2 through a suitable passage hereincomprising pipes 4 and 6 communicating through a valve seat opening 8with which cooperates a valve or controlling member It. Suitableigniting means, herein a pilot flame It issuing from a burner 24, isprovided to ignite the gas or other fuel from the main burner 2.Controlling means for said valve is also provided, said controllingmeans being preferably heat responsive so as to be controllable by thepilot or other heating or igniting means. Herein the valve controllingmeans will preferably comprise an electromagnet and a thermocouple if.

The electromagnet comprises a generally potshaped magnet l1 supportedJorinstance, by the upper wall of the pipe 4 and over the valve I I, whichwill be conveniently formed as an integral part of the armature Illa forthe electromagnet. The magnet I2 is provided with an electromagnetwinding or coil II and the combined valve and armature will preferablybe made as light as possible. The core it and sleeve it of the magnetframe may be integral and will preferably be made of iron or an alloyhaving a very low capacity for residual magnetism. An iron alloy sorghumover 30% of nickel satisfies this con- The magnet winding It willpreferably be made of relatively thick copper wire, 2 mm. or more indiameter. One I end of said winding is conductively connected to themagnet frame while the other end is connected, preferably by arelatively thick copper wire 20, with one terminal of a thermocouple 22.thermocouple is herein conductively connected to the burner 24 formaintaining the pilot flame 26. gas or other fuel being supplied to theburner 24 through a pipe 28 connected to the gas supply. The pipe 26 isherein conveniently connected to the pipe 6 between the'valve seat Illand the main burner 2. The terminal is thus conductively connected tothe magnet frame through the walls of the pipes 26, 6 and 4.

The thermocouple 2'2-is so positioned relative to the pilot flame thatthejunctions or points of union thereof are heated by the pilot flame.

One or more thermocouples may be used.

The valve stem 36 extends through a bearing 32 in the lower wall of thepipe 6 and carries a disc 34 at its free end. This disc 34 is containedThe other terminal of the I the thermoelectric current will cease, orbecome insufllcient to energize the electromagnet sumciently to hold thevalve III in open position and the valve will drop or be otherwise movedto closed position, closing the valve seat opening 6 and therebyshutting off the'gas supply tothe burner 2 and pilot 26.

To light the burner 2 the plug or button 46 is pressed inwardly in thecylinder part 46, thus moving the piston 36 inwardly. The air in thecylinder 36-being thus compressed the disc 54 will be raised or unseatedfrom the port 56 against the tension of the spring 56 and air will thusescape from the cylinder 36 through the port 66. Before the piston 36reaches its inwardmost position the spring 42 engages the disc 34 andactuates the valve and armature member Ill, lila in a cylinder 36 whichalso contains a piston 36.

The piston 38 carries a'central boss 40 supporting a helical spring 42below the disc 34 and preferably out of contact with the disc 34 whenthe valve III is in open or operative position. The rod or stem 44 ofthe piston 36 extends through a transverse wall in the cylinder 36 andits outer end is connected to a plug or button 46 which has sliding fitin the cylindrical part 46. A helical spring 49 surrounds the stem 44,one end of this spring engaging the end of the plug or button 46 and theother end engaging the transverse or end wall of the cylinder 36, thespring 46 thus tending to press the piston 36 outwardly.

It will be apparent that by pressing inwardly upon the outer end of thebutton 46 the piston 36 will be moved inwardly and if the valve andarmature forming member l6, Illa has dropped, continued pressure on thebutton 46 will move the armature Illa to attracted position and thevalve portion HI thereof to open position. I

The damping or retarding means for delaying movement of the armature toretracted position and the valve to closed position for a suflicientlength of time to permit the pilot or other burner to be lighted and theheat of the flame thereof on the thermocouple to generate suflicientthermoelectric current to hold the armature in attracted position andthe valve or other controlling member in open or operative position,comprises a port 50 opening through the lateral wall of the cylinder 36into a chamber 52. The chamber 52 contains a disc 54 and a helicalspring 56 one end of which engages the disc 54 and the other end ofwhich engages the opposite wall of the chamber 52 and thus tends topress the disc against the port 50 or into position closing the port.The disc 54 is provided with a small throttling or choke port 56, theentire dashpot combination forming a non-return or one way valve.

The operation of the illustrated embodiment of the invention is asfollows:

The valve III being in open position, with the armature portion Mathereof in attracted position against the magnet frame l2 as shown, itwill be maintained in that position as long as the pilot burner 2 and isignited by the pilot flame. Should the pilot 26 become extinguished forany reason outwardly, the armature portion into contact with the magnetframe l2 and the valve portion thereof into open position. In thussetting the valve and armature member to operative position the spring42 is compressed so that when the armature is in attracted position andthe valve in open position the spring 42 will be tensioned between thedisc 34 and the piston 36.

The burner 2 and pilot being now supplied with gas, can be lighted. Thepilot them heats the thermocouples 22, thus energizing the electromagnetwhich will then maintain the valve l6 open and the armature in attractedposition as long as the pilot is lighted. The reset button or plug 46may be released immediately following actuation of the valve andarmature to operative position, and the spring 42 will continue to holdthe valve in open position and the armature in contact with the magnetframe of the electromagnet until the latter becomes sumciently energizedto hold it there, for as previously exhausted air from the cylinder 36can reenter the cylinder only very slowly through the throttling port 56in the disc 54, the piston 36 can drop or move outwardly only veryslowly. Consequently before the compressed spring 42 can expandsufficiently to allow retraction of the valve and armature HI ,lila, thethermoelectric current will have become sumciently strong to hold thevalve in open position. The pilot or other igniting or. heating meansand the thermocouple or thermocouples should be relatively positioned sothat the thermal junction or junctions will be well and reliably heated.

The reset button 46 is' mounted for reciprocatory movement coaxiallywith respect to the damping or retarding piston 36 and the button 46 andpiston 36 are coaxial with respect to the electromagnet and the valveand armature. Moreover, the retarding means is normally free of thevalve and armature, so that when the parts are positioned as shown inthe drawing and the electromagnet is operative to hold the armature inattracted position, the electromagnet is not required also to hold thedamping piston 36 in its inwardly projected position in the cylinder 36.With the parts positioned as shown in the drawing the electromagnet isalso free of the spring 42. The damping means is out of the path of thefuel supply and is enclosed and sealed therefrom.

- We do not intend to be limited-to the precise details shown ordescribed.

We claim:

1. In a. safety device for fuel burners of the self-contained typeemploying thermoeiectrical actuation, a passage through which the .fuel,flows to the burner, a valve in said passage, an

' electromagnet for normally holding said valve in open position andadapted to be energized by valve and disconnected from said valve foroutward movement free of said valve so that the electromagnet may holdsaid valve open without also holding said piston in its inward position.

2. In a safety device for fuel burners of the self-contained typeemploying thermoelectrical actuation, a passage through which fuel flowsto the burner, a valve in said passage, an electromagnet for normallyholding said valve in open position and adapted to be energized by athermocouple subjected to the'heat of a flame in proximity to saidburner, a cylinder closed against the entry of fuel into the same fromsaid passage, a stem extending from the valve into said cylinder, apiston operable in said cylinder to retardmovement of said valve toclosed position and disconnected from said valve for outward movementfree of said valve, a reset stem extending from said piston and out ofsaid cylinder, a reset button on said stem, and a spring interposedbetween the piston and the stem extending from the valve for resettingsaid valve to open position upon inward movement of said reset button.

3. m a safety device for fuel burners of the self-contained typeemploying thermoelectrical actuation, a passage through which fuel flowsto the burner, a valve in said passage, an electromagnet for normallyholding said valve in open into said cylinder in the outward movement ofthe piston.

4. In a safety device for fuel burners, 'a passage through which fuelflows to the burner, a

valve in said passage, a cylinder, a stem ex-' tending from the valveinto said cylinder, a piston operable in said cylinder to retardmovement of said valve to closed position and disconnected from saidvalve for outward movement free of said valve, a reset stem extendingfrom said piston and out 01' said cylinder, a reset button on said stem,and means interposed between the piston and the stem extending from thevalve for resetting said valve to open position upon inward movement ofsaidreset button.

5. In combination, a thermally responsive safety device provided withthermally responsive means and with a controlling member having anoperating position and a safety position,,.

means for resetting said controlling member to operating position, andmeans adapted for actuation by said resetting means and at all timesdisconnected from and wholly free of said controlling member and saidthermally responsive means for retarding movement of said controllingmember to safety position upon resetting said controlling member tooperating position.

6. In combination, a thermally responsive safety device provided withthermally responsive means and with a controlling member having anoperating position and a safety position,

' means for resetting said controlling member topositionandadaptedtobeenergizedbya' thermocouple subjected to the heatof a flame in proximity to said burner, a cylinder closed against theentry of fuel into the same fromsaid passage, a stem extending from thevalve into said cylinder, a piston operable in said cylinder to retardmovement of said valve to closed position and disconnected from saidvalve for outward movement free of said valve, a reset stemextendingfromsaidpistonandoutofsaid cylinder, a reset button on saidstem, a spring interposed betweenthe piston and the stem extendingfromthe valve for resetting said valve to open position upon inwardmovement of said reset button, and means for letting air out of saidcylinder-in theinward movement of the'plltonandforprevenflngtheadmissionofair operatlng'positio and meansadapted for actuation by said re etting means and at all timesdisconnected from and wholly free of said controlling member and saidthermally responsive means for retarding movement of said controllingmember to safety position upon resetting said controlling member tooperating position, said retarding means being carried by and operativewith said resetting means.

7. In combination, a thermally responsive safety device provided withthermally responsive means and with a controlling member having anoperating position and a safety position, means for resetting saidcontrolling member to operating position, means adapted for actuation bysaid resetting means and at all times disconnected from and wholly freeof said controlling member and said thermally responsive means forretarding movement of said controlling member to safety position uponresetting said con- "trolling member to operating position, a stemextending from said controlling member, and a spring interposed betweensaid stem and said

